2003-01-08 04:00:00 PDT San Diego -- In the complex battle to halt the growing epidemic of childhood obesity, breast-feeding is emerging as a simple but apparently effective weapon.

Results of a study presented Tuesday at a statewide conference on childhood obesity shows that not only do breast-fed babies learn early on how to control their appetites, but they might also experience metabolic and hormonal changes that make them better equipped to maintain ideal weight later in life.

The comprehensive analysis of several new pieces of research, released at Tuesday's meeting of 1,100 health care professionals and educators, provides the most compelling link for breast-feeding and weight control to date.

Kathryn Dewey, nutrition professor at UC Davis, analyzed breast-feeding research from several years of study that included tens of thousands of children from seven countries. One of the most significant pieces of data came from the University of Glasgow, where researchers studied some 32,000 Scottish children and found that those who were breast-fed had a 30 percent reduction in obesity rates.

Breast-feeding is certainly not the sole answer to the childhood obesity epidemic. Researchers say the clearest predictor of which children will grow up too fat remains genetic -- that is, children with fat parents are five times more likely to be overweight. And kids who eat unhealthy diets and don't exercise will become overweight no matter what shape their parents are in.

"The role of breast-feeding is still small compared to those factors, but it's still an important part of the package," Dewey said.

The reasons for breast milk's apparent preventive effects aren't entirely clear, but Dewey suspects that babies who are breast-fed are better able to program themselves to stop eating when they are full. Parents who bottle-fed often over-feed their children, Dewey said. Over-feeding in infancy can increase the number of fat cells.

Her study will be published in next month's Journal of Human Lactation.

In addition, babies raised on formula have higher insulin levels and prolonged insulin response, which have been associated with weight gain. And some research shows that breast-fed babies have higher levels of leptin, a hormone that regulates appetite, Dewey said.

In another piece of research discussed at the conference Tuesday, Adam Drewnowski, a medical and epidemiology professor at the University of Washington, said feeding a child formula helps develop their natural affinity for foods that are fatty and sweet. Formula is made with sucrose -- essentially, table sugar -- which is much sweeter than lactose, the sugar found in breast milk.

"Our preferences for taste are hard-wired," he said. "Infants prefer sucrose over less-sweet lactose. And infants will over-consume such sweet solutions."

Breast-feeding has gained popularity since the 1960s, when only about a quarter of new mothers used the method. In 2001, 83 percent of new mothers in California tried breast-feeding in the hospital, but only about 42 percent continued to use breast milk exclusively once they went home.

The news on breast-feeding and weight control was not a tough sell to conference attendees. At the beginning of the three-day event, organizers announced that a lactation room and breast pumps would be available for the duration.

And if preventing weight gain isn't enough of an argument for parents considering the breast over the bottle, many Northern California parents will appreciate this side effect: A study from the nonprofit Monell Chemical Senses Center in Philadelphia showed that babies exposed to the varying flavors in breast milk develop better palates later in life and are more willing to try new foods.